Sensor arrangement for the control of implantable devices

Abstract

A sensor arrangement for controlling an implantable device, such as a heart pacemaker, has a number of individual sensors connected to an evaluation circuit through a catheter having at least two leads. The sensors are respectively activated in chronological succession by a shared control circuit, with both the sensors and the control circuit being arranged in the catheter. The corresponding measured signals are transmitted via the same leads, and also being offset chronologically. The arrangement permits a number of sensors to be connected to a catheter while maintaining only two lines in the catheter, so that the flexibility and reliability of the catheter, which are best with the fewest possible leads, remain unimpaired.

We claim as our invention: 
     
       1. An apparatus for medically treating a patient comprising: an implantable device which supplies a medical treatment to said patient, said device having at least one variable function;   a catheter connected to said device and also implantable in said patient, said catheter having a plurality of leads therein;   a plurality of sensors which respectively generate measured signals corresponding to different body parameters of said patient contained within said catheter;   control means in said catheter for successively respectively connecting said sensors across only two leads of said plurality of leads and thereby activating said sensors chronologically offset;   an evaluation means disposed in said implantable device remote from said sensors and connected to said sensors by said catheter for generating a signal for use in varying said variable function from said measured signals; and   means for transmitting said respective measured signals from each activated sensor chronologically offset to said evaluation means via no more than said two leads.   
     
     
       2. An apparatus as claimed in claim 1, wherein said control means includes a plurality of switches respectively connected to said sensors, and means for operating said switches in a selected sequence. 
     
     
       3. An apparatus as claimed in claim 1, wherein said control means includes means responsive to signals from said evaluation means for activating said sensors. 
     
     
       4. An apparatus as claimed in claim 3, wherein said evaluation means includes means for generating coded trigger signals, and wherein said control means includes a decoder which receives said coded trigger signals via said leads and which causes activation of said sensors based thereon. 
     
     
       5. An apparatus as claimed in claim 1, wherein said control means includes means for coding said measured signals before transmission to said evaluation means so that the sensor which is the source for each measured signal can be identified by said evaluation circuit. 
     
     
       6. An apparatus as claimed in claim 5, wherein said means for coding includes a timer circuit. 
     
     
       7. An apparatus as claimed in claim 6, wherein said timer circuit consists of a counter connected to each of said sensors and a pulse generator connected to said counter. 
     
     
       8. An apparatus as claimed in claim 5, wherein said means for coding is a means for pulse phase modulation coding. 
     
     
       9. An apparatus as claimed in claim 8, wherein said means for coding includes means for generating a zero mark at a beginning of each measuring period, and wherein said means for pulse phase modulation is includes means measuring the distance of each coded trigger signal from the zero mark. 
     
     
       10. An apparatus as claimed in claim 1, further comprising means for encoding said measured signals using amplitude modulation. 
     
     
       11. An apparatus as claimed in claim 1, further comprising means for coding said measured signals using pulse duration modulation. 
     
     
       12. An apparatus as claimed in claim 1, further comprising means for coding said measured signals using pulse code modulation. 
     
     
       13. An apparatus as claimed in claim 1, further comprising a memory connected to each of said sensors and a signal transducer connected to an output of said memory, said memory storing each measured signal from a sensor upon activation of a sensor, and the stored measured value being converted by said signal transducer following completion of a measurement into a form for evaluation by said evaluation means. 
     
     
       14. An apparatus for medically treating a patient comprising: an implantable device which supplies a medical treatment to said patient, said device having at least one variable function;   a catheter connected to said implantable device and also implantable in said patient, said catheter having a plurality of leads;   a plurality of sensors contained within said catheter, each sensor generating a measured value signal upon activation thereof corresponding to a respective body parameter of said patient;   a like plurality of switching means respectively connected to said sensors and also contained within said catheter for connecting said sensors across only two leads of said plurality of leads;   an evaluation means disposed in said implantable device remote from said sensors and connected to said sensors by said catheter for generating a signal for use in varying said variable function from said measured value signals;   a counter means connected to each of said switches for operating said switches to activate said sensors in a selected sequence in response to an input signal, each of said sensors, when activated, supplying its measured value signal via no more than said two leads to said evaluation means;   and means for generating said input signal for said counter.   
     
     
       15. An apparatus as claimed in claim 14, wherein said means for generating said input signal is a pulse generator contained within said catheter and connected to said counter. 
     
     
       16. An apparatus as claimed in claim 14, wherein said evaluation means includes means for generating a coded trigger signal, and wherein said means for generating said input signal is a decoder connected across said leads within said catheter and having an output connected to said counter, said decoder decoding said coded trigger signal from said evaluation means and operating said counter based on the decoded signal. 
     
     
       17. An apparatus for medically treating a patient comprising: an implantable device which supplies a medical treatment to said patient, said device having at least one variable function;   a catheter connected to said implantable device and also implantable in said patient, said catheter having a plurality of leads therein;   a plurality of sensors contained within said catheter, each sensor generating an output signal upon activation thereof corresponding to a respective body parameter of said patient;   a like plurality of switching means respectively connected to said sensors for connecting said sensors across only two leads of said plurality of leads;   an evaluation means disposed in said implantable device remote from said sensors and connected to said sensors by said catheter for generating a signal for use in varying said variable function from said output signals of said sensors;   a counter means connected to each of said switches for operating said switches to activate said sensors in a selected sequence based on a input signal to said counter each of said sensors when activated, supplying its output signal via no more than two leads to said evaluation means;   means for generating said input signals; means connected to each of said sensors, to said counter and to said leads for encoding the output signals of said sensors for transmission to said evaluation means to identify the sensor producing the output signal.   
     
     
       18. An apparatus as claimed in claim 17, wherein said means for coding is a memory having means controlled by said counter for individually connecting said memory to said sensors in said selected sequence, and a signal transducer means connected to an output of said memory for converting the output of said memory into a signal for transmission to said evaluation means via said leads.